Radio circuits



Oct. 13, 1931. w. .LAPoLSfDoRor-'F v1,827,332

RADIO CIRCUITS Filed July e, 192e INVENToR BY j ATTORNEY.

Patentedv Oct. 1,3', 1931'v .i wLAnIMIR: J. rotnonorrgor; CHICAGO, ILLINOIS,` IAssIGfiSTOR frol JOHNSON LABOR@ 55" TORIES, .INCORPORATEE or; CHICAGO, ILLINOIS, A "CORPORATION OFILLI-NOIs- RAISIOs oInOUITs Appimationnied Juiys; 192e; seriai'No". 120,733.

The `invention relates' to --radio-frequency circuits, and provides means for eliminating the undesirable feed-back effects throughthe i audions of such circuits, and for apportioning the energies of y output circuits.

i The invention willpbe better understood if reference be made to theaccompanying drawings, in whiclI-,

Figuref1,'is. a schematic drawing ofthe 10y circuitarrangement ofthis invention, and Figure 2', is a` second view ofthe same'circuit, arranged'in a form to *clearly show the balanced circuit of kthis invention;

Figure 1, shows ya newv arrangement, where 15 the undesirable Capacity effects are eliminated, providing that the two audions cir-j cuits shown have substantially the samein-rk ternal capacity Or meansto make their capacities equal. rlhe incoming kvoltage vz is ap- 'zo plied to the winding 1 of a transformer whose .f

secondary winding 2 with condenser?) forms grid circuits of audions 4 and'5.-

The grids'of both audions are bridged by Aa non-inductive resistance 6,A the middle part kzof which resistance isbrought to aY biasing Y battery 7 in order Vto keep the grid potential negative with respect tothe filament and Vprevent distorting effects.l

The plates of both tubes may be connected 23o to ya common plate battery. 8 through two separate andy non-inductively `related wind? ings 9 and .10, wound intwo transformers lwhose secondaries,f11 and 12, supply ,out-,put

` voltages V0 1 and 'Vo 2 to succeeding auing system. Y y A i In yFigure 2, the sameV arrangement is schematically represented in the convenient y *forinof a VVVheatstone bridge; Winding 1 40 15 and 16 ofthe bridge, and distributed to four branches 17, 18, 19 and 20,-the noninductive resistances 6, of branches 17 and y y Y Y A.

through their respective windings 9. and 10Q es,

v13 ,.bveing many times lgreater'than the re- .cation may be connected toiny system in 'tector. i

yque'ncy asthe yincoming signal; 1 The'impedd Vance ofl this circuit 2vand 3; when tuned yto dions or pair of audions the radioreceivf relatedto'winding 2 and connected. to points y. v ,Y v ,Y

{Ampliiied voltages of same frequencies are sistances of branches 19 and 20.v gIn the `branches 19 and'20., are shown twoaudions.

4 and 5, and their respective plate windings, v 9 and 10. Output voltage is appliedtotwo separate and nOn-inducti'vely v related'f' winda ings 11 and V12in whichby varying` the rel ysistance ofthe branches 17,` 18, desired difer- .v encesof potential may be established irre- K .spective of the balancing of the audions. .The arms of thebridge 17 '18, 19 and 20may be' sochosen that there will-be no' potential difference betweenpoints `15 and 16 when' an E. `M. F. is appliedto windings9'fand 10 or windings V11 and y12, Ithus' eliminating'the undesirable "feed-back i effectsv through the audio'ns.n y if j f I If branches 19'and 20 are unbalanced, compensat-ingy Vadjustment 4may 'be madel in branches 17 and 18, by'theadj'ustable connection of the battery 7.

A single stage of radio1 frequency amplifiwhich Vcase windings l11 `land 12vwill be4 con-y nectedin series laiding (V0 1 and'V0f2) and will 'bexthe in-'p'ut circuit to the succeeding i stage of radio frequency amplification or .de-V i TheA actionof the circuit rwill be under-Y v stoodfrom Figure 2. f'

i Incoming: radio frequency signal' apry, plied to winding lfas' mi and isinductive'ly transferred to winding 2 whichisinthe diagf ona'1`22 ofthe bridge.l y'VVin'ding2 if associated with condenser 3 forms anoscillatry` circuit 2 andfrespondingtothe same freresonance, -.is very lowfascompared withresistances and impedances Ofbranches 17, 18, y19,' 2O and therefore, the bridge'at its 'point 15 and 16 acts' as a voltage lamplifying device, th'e voltage variations *beingV appliedk on thegrids ortubes 4 and' 5T simultaneously and of ,oppositesign However', 'resistanc'es of *17' and 1,8, lpermit battery ,7,11tomaintain grids y Y oftubes atV negative potential. C9o

produced by. plate-circuits.- yThe plate cur* rentsof both-.tubeshave their useful paths and battery 8 back toiilament circuit indiag- "onall 21j .Part of this-plate current leaks through capacitiesof tubes4'andy-..5'baclrinto i undesirable oscillations 1 in lthe circuit 2 'and input@circuit'ff2 and `Sand tends to produce *L due to the capacities of the tubes are substantially equal the feed back current affects points 15 and 16 equally and in opposite direction so that undesirable oscillations will be eliminated. When the said impedances are not equal the balance of diagonal 22 can be obtained by adjusting non-inductive resistance 6, constituting branches 17 and 18. These resistances may be chosen near to the order of said impedances of tube capacity at high frequency.

The same balancing effects will be attained if feed back currents occur in winding 11 and 12 and the same adjustments in the bridge are made.

Under some conditions, it may be desirable to so vary the adjustable connection of the battery 7 that the branches 19 and 20 are unbalanced and that, consequently, the windings 9 and 10 and 11 and 12 are unequally affected by incoming signals.

The system as described may be used for radio frequency amplication. rlests show that many stages of cascade amplification can be successfully controlled without objectionable oscillations, and that it is practical to place double-stage amplification between ordinary single stages.

Having thus described my invention, I claim:

1. In a radio-frequency apparatus, means for balancing the inter-electrode capacities of two audions consisting of two audions disposed in two branches of a Wheatstone bridge, two non-inductively related plate windings also disposed in said branches of said Wheatstone bridge, adjustable impedances disposed in the other two branches of said Wheatstone bridge, an input circuit constituting one diagonal of said bridge, and sources of current and filaments Vof said au dions constituting the other diagonal of said bridge.

2. In a radio-frequency apparatus, means for balancing the inter-electrode capacities of two audions consisting of two audions disposed in two branches of a Wheatstone bridge, two non-inductively related plate windings also disposed in said'branches of controlled by an adjustable tap connected with a biasing source.

4. A system, including the four arms and the diagonals of a Wheatstone bridge, an input circuit of which one diagonal of said bridge is an element, two audions and their plate windings arranged in adjacent arms of said bridge, and the other two arms of said bridge constituting variable serial impedances connected across said input circuit, a biasing source of energy disposed in the other diagonal of said bridge, and two out-put windings inductively related to said plate windings.

In testimony whereof I aliiX my signature.

WLADIMIR J. POLYDOROFF.

said Wheatstone bridge, adjustable imped- 

